262. Human cumulus cell gene expression as a marker of clinical embryo grade

Abstract

In Australia, Assisted Reproductive Technology (ART) accounts for ~3% of births. However, the success rate remains around 65% for women under 35 years of age, hence multiple embryo transfer is frequently preferred to improve the probabiity of achieving a term pregnancy. A biochemical marker for oocyte and embryo developmental potential would augment successful pregnancy outcomes following IVF/ICSI by optimising oocyte and embryo selection, therefore increasing the number of single embryo transfers (SET) performed in ART cycles. Changes in expression levels in human cumulus cells may reflect the quality of their enclosed oocyte. We investigated cumulus cell gene expression and subsequent embryo development to find a marker of embryo quality. Paired samples of cumulus cells were collected from oocytes that progressed to embryos of either high or low grade from eleven IVF/ICSI patients. Following cumulus oocyte complex retrieval cumulus cells were trimmed from the oocyte, and all oocytes and resulting embryos were cultured and tracked individually. Cumulus cell gene expression was assessed using a real-time RT–PCR assay, measuring expression of cyclooxygenase 2 (COX2; PTGS2), Pentraxin 3 (PTX3), Versican (VCAN), Tumour Necrosis Factor Alpha Induced protein 6 (TNAIFP6; TSG6), Lactate Dehydrogenase A (LDHA), Phosphofructokinase Platelet (PFKP), Gremlin (GREM1), Glyceraldehyde-3-Phosphate Dehydrogenase (GAPDH) and 18S rRNA. Standard curves using plasmid subclones for each target were run to assess copy numbers of genes. Embryo morphology was assessed by an embryologist and correlated with relative gene expression. Cumulus cell gene expression was altered in cumulus cells from oocytes which subsequently developed into higher quality (Grade 1 and 2) embryos compared with cumulus cells from oocytes which developed into lower quality (Grade 3 and 4) embryos. This may lead to establishment of markers prognostic for developmental outcome, facillitating more reliable selection of higher quality embryos, increasing single embryo transfers and improving health outcomes from ART.